This invention relates to a bag having an oxygen absorbent, characterized in that at least part of the material constituting the bag is composed of a film having a plurality of fine openings, and being gas-permeable, but water-impermeable at one atmospheric pressure. The bag is used for preserving an aqueous liquid or semi-liquid material, such as foodstuffs and other materials.
In order to preserve foodstuffs, such as soy sauce, Japanese sake, sauce, wine, beer, juice, vinegar, etc., it is necessary to prevent the foodstuffs from getting moldy and from putrefying. In the prior art methods, the gas present in the inner part of a content-charged container was replaced by an inert gas or the container was sterilized. However, replacement of oxygen by an inert gas requires large-scale apparatus and sterilization of the filled container may cause change in quality of the contents. Additives, such as antioxidants, have been used for preserving foodstuffs. However, recently, governments have started to regulate the use of additives for foods, since some additives have been found to be injurious to humans.
Molds or eumycetes, bacteria and higher organisms such as insects tend to disturb preservation of foodstuffs. These mold eumycetes, bacteria and insects live and grow in the presence of oxygen and cause putrefaction and change in quality of foodstuffs.
Therefore, if oxygen can be selectively removed from the empty space of the filled container, the problems of putrefaction and change in quality of foodstuffs can be overcome, and it will become possible to preserve foodstuffs for extended periods.